The evil servo is truly evil. It's hard to imagine that the engineers who designed a car as good as a W123 MB would stick that Rube Goldberg piece of crap under the hood to control the heat/ac.

I replaced mine twenty years ago. When it went bad again, I just disconnected it. I live in perpetual summertime so I don't use heat. I wired shut the hot water valve on the firewall and run the ac on Defrost. The Defrost by-passes all of the climate control nightmare. It is a direct electrical connection to the blower and the compressor.

Richard